FIELD OF THE INVENTION
The invention relates to an adjusting device for a gripper opening cam in a chain delivery of a sheet-fed printing press, wherein the gripper opening cam is pivotally guided in a bearing and is connected by a coupling transmission or linkage to one of a pair of threaded nuts of a combination of a lefthand and righthand thread of an adjusting shaft screwable into a fixedly supported other threaded nut of the combination.
Such an adjusting device has become known heretofore from the published German Patent Document DE 43 35 230 A1. The gripper opening cam, as in the published German Patent Document 30 02 591 C2, is disposed so as to be pivotable about an approximately horizontal axis. The combination of the lefthand/righthand thread includes a first threaded nut, which is braced in the machine frame and has a threaded spindle of the adjusting shaft threaded therethrough, and a second threaded nut having a thread running counter to the first threaded nut. The second threaded nut is disposed on the coupling transmission or linkage and has a correspondingly oppositely directed threaded spindle of the adjusting shaft threaded therethrough, so that changes in the rotary angle have the effect upon the coupling transmission or linkage of doubling the thread pitch. The adjustment is generally performed manually through the intermediary of a hand wheel disposed on a free end of the adjusting shaft. Whatever position has been set is indicated directly on the adjusting shaft or on the hand wheel.
From the German Patent 818 365, an hydraulically operated motorized adjusting device for automatically adapting the gripper opening cam position to the machine rpm has become known heretofore, but it is very complicated and does not have the advantages of the mechanically operative adjusting device of the aforementioned German Patent Document DE 43 35 230 A1.